FreeBSD/Linux Kernel Cross Reference
sys/powerpc/powermac/vcoregpio.c

     /*-
      * Copyright (c) 2009 Nathan Whitehorn
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
     * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
     * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/module.h>
    #include <sys/bus.h>
    #include <sys/conf.h>
    #include <sys/cpu.h>
    #include <sys/kernel.h>
    #include <sys/sysctl.h>
    
    #include <dev/ofw/ofw_bus.h>
    #include <dev/ofw/openfirm.h>
    
    #include <powerpc/powermac/macgpiovar.h>
    
    static int      vcoregpio_probe(device_t);
    static int      vcoregpio_attach(device_t);
    static void     vcoregpio_pre_change(device_t, const struct cf_level *level);
    static void     vcoregpio_post_change(device_t, const struct cf_level *level);
    
    static device_method_t  vcoregpio_methods[] = {
            /* Device interface */
            DEVMETHOD(device_probe,         vcoregpio_probe),
            DEVMETHOD(device_attach,        vcoregpio_attach),
            { 0, 0 },
    };
    
    static driver_t vcoregpio_driver = {
            "vcoregpio",
            vcoregpio_methods,
            0
    };
    
    static devclass_t vcoregpio_devclass;
    
    DRIVER_MODULE(vcoregpio, macgpio, vcoregpio_driver, vcoregpio_devclass, 0, 0);
    
    static int
    vcoregpio_probe(device_t dev)
    {
            const char *name = ofw_bus_get_name(dev);
    
            if (strcmp(name, "cpu-vcore-select") != 0)
                    return (ENXIO);
    
            device_set_desc(dev, "CPU Core Voltage Control");
            return (0);
    }
    
    static int
    vcoregpio_attach(device_t dev)
    {
            EVENTHANDLER_REGISTER(cpufreq_pre_change, vcoregpio_pre_change, dev,
                EVENTHANDLER_PRI_ANY);
            EVENTHANDLER_REGISTER(cpufreq_post_change, vcoregpio_post_change, dev,
                EVENTHANDLER_PRI_ANY);
    
            return (0);
    }
    
    static void
    vcoregpio_pre_change(device_t dev, const struct cf_level *level)
    {
            if (level->rel_set[0].freq == 10000 /* max */) {
                    /*
                     * Make sure the CPU voltage is raised before we raise
                     * the clock.
                     */
                    macgpio_write(dev, GPIO_DDR_OUTPUT | 1);
                    DELAY(1000);
           }
   }
   
   static void
   vcoregpio_post_change(device_t dev, const struct cf_level *level)
   {
           if (level->rel_set[0].freq < 10000 /* max */) {
                   DELAY(1000);
                   /* We are safe to reduce CPU voltage now */
                   macgpio_write(dev, GPIO_DDR_OUTPUT | 0);
           }
   }
   

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